第章状语从句学习指导状语从句在句子中作状语，用来修饰主句或主句的谓语。
一般可分为九大类，分别表示时间、地点、原因、目的、结果、条件、让步、比较和方式。
尽管种类较多，但由于状语从句与汉语结构和用法相似，所以理解和掌握它并不难。
状语从句的关键是要掌握引导不同状语从句的常用连接词。
现分别列举如下：状语从句分九类：在这一章节的学习中，要求同学们掌握各类状语从句基本概念，并能够灵活应用第一节时间状语从句1. 时间状语从句用一般现在时表示将来。
连接时间状语从句的连接词有:2. when，while，as均可表示当.... 的时候”when强调特定时间”表示主句谓语动词的动作与从句谓语动词的动作是同时发生的，或从句的动作发生在主句的动作之前；while表示的时间是一段，而不是一点，as多用在口语中，强调同一时间”或一前一后”有时还有随着”的含义。
I'll go on with the work when / come back tomorrow .我明天回来后会继续做我的工作。
When spring came, he felt like a trip.春天来了，他想去旅游。
As spring warms the good earth，all flowers begin to bloom . （as 有随着”的含义）as, when, while 都表示主、从句的动作或状态同时发生，但三者也有区别。
as和when引导的从句既可表示一点时间，也可表示一段时间，从句中的谓语动词既可以是持续性动词，也可以为短暂性动词，经常可以互换使用；while引导的从句通常表示一段时间，从句中宜用持续性动词作谓语。
当从句中的谓语动词为持续性动词时，这三者可以通用（前面例句中已有体现），再如：Mother was worried because little Alice was ill, especially as / when / while father was away in France. 妈妈担心，因为小艾丽思病了，特别是当父亲远在法国的时候。
如果从句和主句要表示一个人的两个动作交替进行或同时完成时，则多用as，可译为“一边……，一边……”。
例如：A. whe nB. how 3) He was riding to schoolA while B. whe n 4) Lucy knew nothing about it A. becauseB. un til5) The policeman asked the childC. whyD. that he was hit by a car this morning.C. asD. so __ h er sister told her.C. ifD. si nee___ cross the street _____________ the trafficHe looked behind from to time as he went. As time goe s on, it ' s getting warmer and warmer..暖了。
I thought of it just as you ope ned your mouth. 示两个短促动作几乎同时发生时，用as 的场合多于当主从句之间表示转折或对比关系时，多用while,She thought I was talk ing about her daughter, while in fact, I was talk ing about my daughter.她以为我在谈论她女儿，而事实上，我在谈论我的女儿。
如果表示从句的动作在主句的动作"之前”或"之后”发生时，多用when (=after ),不用as 或 while 。
此外，when 还含有"at that moment ”的意思( =and then )，引起的句 子不能放在句首，也不能用as, while 来替换。
例如：He was about to leave whe n the teleph one ran g.他正要离开，忽然电话铃响了。
We were watchi ng TV whe n sudde nly the lights wen t out. 我们正在看电视，突然灯灭了。
They had just arrived home whe n it bega n to rain.他们刚至 U 家，天就开始下雨了。
3. till /until ，表示一直到 ........ ”，主从句都用肯定式；表示 直到 ...... 才”，主句否定，从 句肯定。
He worked un til it was dark. 他一直工作到天黑。
He did not get up till his mother came in. 一直到母亲进来他才起床。
4. once 一旦”，by the time 至y •“… 时”。
Once you see her, you will find what I said is true. 一旦你见到她就会发现我说的是对的。
by the time+现在时，主句用将来完成时。
By the time he arrives, we will already have left here. 等他到达时，我们将已离开这儿了。
by the time+ 一般过去时，主句用过去完成时。
By the time he arrived, we had already left here.他到达的时候我们早已离开这儿了。
5. as soon as, the moment 表示从句动作一发生，主句动作随即发生，通常译为 一 就”。
As soon as I finish the work, I'll go to see you. 我一完成工作就会来看你。
She came to the sce ne the mome nt she heard the n ews 她一听至叶肖息就来至 U 现场。
6. since 自'从”， ............ b efore 在' ....... 前”，after 在… 后”，It was not long before 意为 不久”。
since 引导从句用非延续性动词或过去时间点"或过去时间段+ago ”，主句用完成时态。
Since he graduated, he has worked in this city. 他毕业后一直在这个城市工作。
I have n't see n him since last year/ three years ago. 去年以来 /3 年来，我没见过他。
选出最佳答案1) _________ he was listening to the music, John fell asleep.他一边走，一边不时地往后看。
随着时间的推移，天气变得越来越你一张嘴我就知道你要说什么。
(若表 when.)不用 as 或 whee 如：A. AfterB. BeforeC. WhileD. As soon as- 2) How did you try to get to school on time ____________ you missed the school bus.lights tur ned gree n.A. not; whe nB. don't; beforeC. not to; un tilD. not to; since6) The book was so in teresti ng that he had read it for three hours he realizedit.A. whe nB. afterC. un tilD. before7) ____________ we had seen all the animals, we went home.A. The nB. AfterC. ThoughD. While8) She has made many friend ______________ she came to our school.A. beforeB. afterC. sinceD. un til9) —How long has the weather been like this?A. Un til last ni ghtB. Ever since last ni ghtC. Two days agoD. Two days later10) My uncle went to Australia last year. We have n't see n him .A. since almost a yearB. from almost a year onC. after almost a yearD. since almost a year ago11) He was so tired that he fell asleep _____________ he went to bed.A. as ifB. even thoughC. ever sinceD. as soon as12) I knew nothing about the accident ____________ my friend told me yesterday.A. becauseB. sinceC. un tilD. after13) I did n't man age to do it _____________ you had expla ined how.A. un tilB. sinceC. whileD. after[Keys 】1) C 2) A 3) B 4) B 5) A 6) D 7)B 8) C 9) B 10) D 11) D 12) C 13) A第二节条件状语从句1. 条件状语从句用一般现在时表示将来。
引导条件状语从句的连词有:2. 表示正面的条件用if “果”If you don't look after young trees, they will die very quickly.If the museum charges for en try, a lot of people won't be able to visit it.3. 表示否定的条件用unless( =if. .. not) “非，如果不”I shall not go to the cin ema unl ess I finish my homework before eight. 说明：if…not常可以用unless替代。